| 摘要 |
An injector head unit includes one or more drive chains revolving within a common plane mounted on an upper drive sprocket and a lower drive sprocket, wherein at least one of the upper and lower drive sprockets are configured to move vertically to tension the drive chains, and at least one fixed reference point proximate to at least one of the upper and lower drive sprockets, wherein relative positioning of one of the movable upper and lower drive sprockets with the fixed reference point indicates to a user an amount of elongation of the drive chains after a certain period of time. |
